Thanks, Daniel, great testcase.
Suka, Pavel, the problem is because send_signal() only calls a
signal from_ancestor_ns if is_si_special(info), while reparent_thread()
sends SEND_SIG_NOINFO.
Why is the '!is_si_special(info)' check there for from_ancestor_ns()?
-serge
Quoting Daniel Lezcano (dlezcano@xxxxxxxxxx):
> Hi,
>
> I noticed a changed behaviour with the PR_SET_PDEATHSIG and SIGKILL
> between different kernel versions.
>
> With a kernel 2.6.27.21-78.2.41.fc9.x86_64, the SIGKILL signal is
> delivered to the child process when the parent dies but with a 2.6.31
> kernel version that don't happen.
>
> The program below shows the problem. I remember there was were some
> modifications about not killing the init process of the container from
> inside, but in this case, that happens _conceptually_ from outside.
> Keeping this feature is very important to be able to wipe out the
> container when the parent process of the container dies.
>
> #include <stdio.h>
> #include <unistd.h>
> #include <stdlib.h>
> #include <sys/prctl.h>
> #include <sys/param.h>
> #include <sys/poll.h>
> #include <signal.h>
> #include <sched.h>
>
> #ifndef CLONE_NEWPID
> # define CLONE_NEWPID 0x20000000
> #endif
>
> int child(void *arg)
> {
> if (prctl(PR_SET_PDEATHSIG, SIGKILL, 0, 0, 0)) {
> perror("prctl");
> return -1;
> }
>
> sleep(3);
> printf("I should have gone with my parent\n");
> return -1;
> }
>
> pid_t clonens(int (*fn)(void *), void *arg, int flags)
> {
> long stack_size = sysconf(_SC_PAGESIZE);
> void *stack = alloca(stack_size) + stack_size;
> return clone(fn, stack, flags | SIGCHLD, arg);
> }
>
> int main(int argc, char *argv[])
> {
> pid_t pid;
>
> pid = clonens(child, NULL, CLONE_NEWNS|CLONE_NEWPID);
> if (pid < 0) {
> perror("clone");
> return -1;
> }
>
> /* let the child to be ready, ugly but simple code */
> sleep(1);
>
> return 0;
> }
>
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